Clear Solar Power Crookes Radiometer Sun Light Energy Glass Windmill Spinning Vanes

So this floats freely and spins without any noticeable resistance, I'd say approches 300-500 RPM in bright daylight. Will lollygag in slight sun, but it needs quite a bit to get rotating. Its totally cool and what I expected, works as expected. Crystal clear. I see nothing wrong here. Buy one for the kids, it will open thier eyes to "thats JUST THE SUN" no moving parts, nothing complex, just very simple visually perception of...well you tell your kids what you want, but it ain't gonna stopt this from spinning. I understand it, but its still satisfying.

Sweet little radiometer but purchase an extra. One of my three I ordered did not work upon arrival.

Basically silent, also gets spinning really fast in direct sunlight. Only been running for a week but so far so good!

This barely works at all. This only turns, slowly, in full sun. I bought one, returned it and the replacement was just as bad. I've had radiometers before and this one that were completely different. I just returned the second one. Don't bother with this.

As other reviewers have noted, the radiometer arrived with some of the black paint flaking off one of the vanes. The rotor is also out of balance so it wobbles at high speed when n direct sunlight but compared to one I got in Germany about 8 years ago, it spins a lot faster.

Pushed by photons (light)? - No. Hint: Photons have no mass, therefore no "push" effect. Those little photons do possess energy though. So, intelligent people would ask, "So what does push the vanes?". Ans: The globe is almost a vacuum so there is a very small amount of gas inside. The rotating force comes from that gas being heated by infrared radiation (you can put something hot near the radiometer and it will spin with no visible light) with the black side of the vanes absorbing more energy and becoming being hotter than the white or silver side. I will not go into detail here, but the hotter gas is repelled off of the black side which creates a slight positive pressure, and the gas from the cooler white side migrates over the edge to the black side (creating a slight negative pressure on the light side) and replaces the escaping hot gas from the black side increasing the pressure slightly there. Most of this action occurs right near the edges of the vanes. Therefore, more pressure develops on the Black compared to the Silver side! Got it? Whew! Don't feel bad if you didn't figure this out. It took several great physicists many years to figure this thing out (including Einstein). OK, not 100% correct? You physics experts can correct my explanation. Thank You

Está perfecto! Like I always dreamed in my science classes in high school

I use this as a display for solar and people love looking at it and seeing it spin.

文字が十分読める明るさの、カーテン越しの太陽光の中に置いても回転速度が遅く感じる。 白熱電球のもとでは試していないので何とも言えない。

great science toy now i have one

A really amazing piece of decor, works like a charm, I am really interested in this, Great idea.

Yes, it works, but the glass is extremely thin and delicate. The slightest tap will cause the glass to shatter.

I put this in my office in a window sill. It's a neat product to see it spin when it starts to get sunny out.